Compass system



4 Sheets-Sheet 1 .SQL DN Nw P. A. NoxoN COMPASS SYSTEM May 7, 1946. y

4 Sheets-Sheet 3 Filed Dec. 17, 1940 ATTOR'NEY May 7, 1946. P. A. NoxoN COMPASS SYSTEM Filed Dec. 17, 1940 4 Sheets-Sheet 4 INVENTOR Paul )Voxan ATTOR'NEY I sony l paar/olv .runner mrs GEAR BY l Tl/RRET TURRET 800, PORT/0N Patented May 7, 1946 UNITED s'rA'r COMPASS SYSTEM raui A. Nomi, runny, N. J., animo; in Bendix Aviation Corporation,-A Soiith Bend, Ind., a cojrporation oi Delaware Application December 11, 1940, semina. 310,531 f i sentirne.y (cias- 225) This invention `relates to magnetic compasses and more `particularly to compasses vfor dirigible craft having a turret member adapted for rotationtwith respect to the main body portion of the cra Heretofore, magnetic compasses for craft, such as fighting tanks, have been unsatisfactory. Principally because of the insensitivity of the conventional magnetic compass in the iron and steel `body of a tank, and also because of the dimculty of reading the card of the conventional compass during excessive vibration and the conditions of rough usage to which the tanks are subjected. Due to these and other deilciencies, no means, prior yto the present invention, were available by which the angle of train of the gun turret, as Eveil ads bearing of the tank, could be readily ascercompass carried by a crait, such as a tank',- and an indicating and repeating system which will continuously show, not only the magnetic bear- It is an object oi the present invention to pro.-

vide a magnetic compass which will overcome these objections. I

It is another 'object of the present invention to provide a novel type of magnetic compass and.

repeating system by which the bearing oi` acraft,

such asa dirigible tank, and the angle of train of its turret, may be continuously and remotely indicated.

A further object of the'invention lies in the provision of a novel repeating and indicating system for a magnetic compass by which a com- 30 pass course may be manually selected, and which allows'ready comparison ofv the bearinglofthe carrying vehicle and the angle of train vof its gun turret.

These and other objects of the present invention will become readily understood upon a study of the following specification when made in conjunction with the attached drawings, throughout which likeparts are designated by like reference characters. y l y Fig. 1 is a perspective view oi an installation o!` the compasssystem of the present invention, showing a tank in -phantom;.'

Fig. 2 .is a diagram, partly schematic and partly in perspective, of the compass and indicating system, of the present invention; 1

Fig. 3 is an elevational view, partly in section, of an indicator used in the present invention; Fig. 4 is a plan view of the indicator shown in Fis. 3: and l Fig. 5 is andlagram, partly schematic and partly in'perspective, of another embodiment of the -compass system of the present invention.

Generally speaking, in accordance with 'the ing of the carryingvehiclabut also the angle through. which the gunA turret has been revolved with respect to the longitudinal or some other selected axis of the vehicle. ,1, f f

\ Having particular reierenceto Fig. ,1, there is shown atiIl a dirigible tank having a main body portion II, and a turret I2, inwhichmay be mounted one or. more guns` I3.y vTurret I2 is mounted. so as to'be rotatable withrespect to body portion II underthe control vof a gunner, whose station is within turret I2, preierablycentrally thereof.v `VTurret. I2 carries an annulargear member. Il, and body portion :I I- carries suitable `driving means,=not shown.: whereby the gunner may rotate turret i2. A gear-Itis inmesh with gear` member I4, and iis mounted so asto rotate about a fixed Vaxis upon; rotation otturret I2 and gear Il. VA flexible shaft lids-con,- nected, at its upper. end,to gearailvand at.its

*lower end `to pinion I1 in `mesh with-a gear,` I8

mounted onrotor shait .IQ oi ya self-synchronous transmitting means or electrical transmitting device 2n.. vlitotorshaft. I! isco'nnected'atitslowerl endy tol a flexible shaft 2l, which passes into slip-ring houslng.22. Slip-ring connections are taken oil within housing 22 and `led' tomagnetic compasshousing 23 by means of electrical cable 2l. Housing. 23 contains certainM magnetic com.- pass units which are-.shownindetail in lFig. 2, and to which reference` will be made later. A

power supplyand ampliiier unit 2,5 is provided,

and inputvand -outputlconnections to compass housing 23 are carried byan electricE cable 26. Remote. compass indicators. 21 are connected to unit 25 through electricaicables. .:A

An additional remote indicator 2g is connected in circuit with housing 23 and unit 25 by means of electrical cable 30, which isconnected through cable 3i and electrical conductorscarxjled .by ilexible shaitingzi throughfslipfrings within housing 22 andcablesgu vand'28.v AV switch .32 is provided forlconnecting .a course-.setting device 3,3, or course-indicating devicerr29, into and out of the compass'circuit at'y the will vof Ithe gunner. Since Fig, l represents the mechanical installation, rather than an electrical schematic showing, the different conductors are grouped within the housing loi. shafting 2I, and electrical ca bles 24, 26, 28,30 and 32|, more with a view to mechanical, rather` than electrical simplicity, but Fig. 2 clearly.sets iorth the .electrical cirpresent invention, there is provided a magnetic. cuits oi the compass installations shown in Fig. l.

a magnet 35. which may be pivoted at point 35 and floated in any suitable liquid, such as kerosene. A suitable magnet, pivot and float arrangement lis shown in the patent to Weber, et al., 2,008,481, but since the present showing oi' a compass is mainly schematic, no pivot or float is illustrated, and only one magnet (35) is shown. The scale shown ln the Weber patent is unnecessary in the use of the present invention, as no readings are to be taken directly from bowl 34,- which may be opaque, and of metal such as brass or aluminum or of non-metallic material such as Bakelite, etc. Immediately beneath compass bowl 34 there is disposed a magnetic pick-up 31, which is mounted upon shaft 35.v Shaft 35 extends through a transmitting motor 45 and is driven through suitable reduction gearing 4| -by a two-phase induction motor 42. Magnetic pickup device 31 comprises two leg members 43 and 44 of any permeable material, such as Permvalloy or Mumetal and these legs carry exciting coils 45 and 45, which are connected in series by means of conductor 35, and through leads 41 to the output of alternator 45. Magneticpickup device legs 43 and 44 also carry windings 55 and 5| which are connected in series and through leads 52 to the input of vacuum tube amplifier 53, which may be of any well-'known design. 'I'he output of amplifier 53 is connected through leads 54 to one phase winding 55 of two-phase induction motor 42. The other phase winding 55 is connected through leads 51 to the output of alternator 55.

Alternator 45 delivers energy at any particular frequency (for example, 400 cycles per second) and alternator 55 delivers'energy at double the frequency (for example, 800 cycles per second) of alternator 45. Both alternators 45 and 55 are connected by rigid shafting to a D. C. C40

output Aof alternator 55, As more fully explained 1 inthe application, Serial No.- 340,396, filed June 13, 1940, whenever a compass bowl, such as 34, is turned with respect'. to magnet 35, (that is, whenever the heading of the carrying craft is changed) the magnetic pick-up device 31 will cause phase winding 55 to become energized, ro tating shaft 35 until-magnetic pick-up device 31 assumes its normal null position with respect to compass magnet 35. It will be Vreadily understood that since phase 55 is energized only when this null relation is disturbed, then selfrotation of motor 42 is not possible when'magnet 35 and magnetic pick-up device 31 are in their predetermined null relation. Phase 55 is constantly energized by alternator 55, but, of course, rotor 55 of induction motor 42 'cannot be rotated when vonly one phase 1.5. energized.

It is above stated that magnetic pick-up device 31 will be rotated to a null position, that is, with the longitudinal axis of magnet 35 at right angles to the axis of magnetic pick-up device 31, as defined by a straight line, including legs 43 and 44. The device 31 is termed a magnetic pick-up device since its function is to periodically shut out and admit lines of fiux from an external field when it is placed within the field. It is obvious that in the null relation the magnetic lines of the field of magnet 35 are all at right angles to the longitudinal axis of magnetic pick-up device 31 and, therefore, no lines are induced to thread Compass bowl 34 (within housing 23) contains through legs 43 and 44, as the shortest path (that is, the path of lowest reluctance) from one pole to the other of magnet 35 will be across magnetic pick-up device 31, and not longitudinally thereof. When, however, the carrying craft turns, either leg 43 ror 44, depending upon whether the craft makes a left or right turn, will be advanced. upsetting the right angle or null relation between the field of magnet 35 and magnetic pick-upy device 31.

We may assume for the sake of explanation, that when magnetic pick-up device 31 is turned `clockwise by the carrying craft, the direction of the lines of force through magnetic pick-up device 31 is'such that le`g43 becomes an N pole, with respect vto leg 4 4 ,`.which will then be an S pole. Therefore, when a current is set up in coils 55 and 5|, due-to the change of reluctance of magnetic pick-up device 31 by the periodic saturation and desaturation of the central portion thereof, by

, means of current from alternator 45 carried through coils45 and 45, ,we will assume that the current, when amplied in amplier 53, and led to phase winding 55, will be so related to the current in phase winding 55 as to cause rotation of rotor 50 and shaft 35 in'a counter-clockwise position, until the null relation is again established, at which .point none of the field of magnet 35 threads magnetic pick-up` device 31 and, therefore, no current is induced in windings 55 and 5|. NowI if the craft turns to the right. leg 44 will be advanced in a counter-clockwise direction and it now becomes an N pole and leg 43 now becomes an S pole so that the current in coils 5I and l5|) is in the opposite direction (since it is .fundamental that the direction of the current in a coil reverses upon reversal of the direction of the magnetic field cutting the coil) and the current in phase winding 55 is ln the opposite direction, and rotor 55, along with shaft 35, will rotate in a clockwise direction to restore the null relation. Due to the fact that a voltage is set up in coils k5|) and 5|, not only upon saturation but also upon desaturation of the central portion of,

magnetic pick-up device 31, and since for every half cycle of current from alternator 45, there will be one complete cycle of saturation and desaturation, the-frequency of the current in coils 55 and 5|, and therefore in phase winding 55, will be double the frequency of alternator 4I, and

yfor this reason it is necessary thatphase winding 55 be energized at double the frequency of alternator 45, and of course as stated above, alternator 55, having twice the frequency of alternator 45, is provided for excitation of phase winding 55.

lIt should be understood that alternator 43 and `excitingcoils 45, 45 do notestablish a magnetic field that will cut coils 55 and 5|, but will saturate and desaturate the central portion of magnetic pick-up device 31 so that the reluctance to the field of magnet 35 is alternately high and low, causing a change in the number of flux lines cutting coils 55 and 5| due to the presence of flux from the external field. l

In rotating magnetic pick-up device 31 to'a null position, induction motor 42 turns shaft 35 which also carries rotor 5| of transmitter 45.

` ground and leads 54 to the stator 55 of receiver 55 and induce in rotor 51 currents vwhich will cause rotor 51 to move azimuth indicating scale 55 by an angular amount equal to the angular type usually employed on a ship's compass is to be applied to the compass needle 35. For this purpose, there is provided a compensating chamber |04, mounted upon bowl 04, in which there may be arranged a series of magnets having axially manually adjustable magnetic screens or sleeves mounted thereon to form a compensating system such as that disclosed in the patent to Urfer, No. 1,933,194. Substantially permanent compensation for magnetic deviation may be carried out by swinging the body II through 360 degrees and making indicated magnetic bearings (at selected points throughout 360 degrees) agree with known magnetic headings in the manner commonly followed for the compensation of marine vessels. After compensation of tank body I I, the readings of scales 60, and 50" will be thereby corrected for magnetic deviation caused by body Portion I I.

It has been found that the proximity of iron in the gun I3 and turret |2 to compass magnet 35, causes additional distortion of the earths field in the vicinity of the compass, which may change as the angle of train is changed, and thus the indicated bearing of body portion II may change while turret I2 is rotated, even though body portion I I is stationary. In order to correct for the erroneous indication due to rotation of an uncompensated turret l2, an additional magnetic compensator, which is rotated upon movement of turret I2, will react upon needle 35 to introduce the proper correction to overcome the magnetic influence of turret rotation upon the readings of scales 60, etc.

This additional compensator is manually adjustable and comprises a chamber |05 mounted upon a shaft |00 connected to rotor member |01 of self-synchronous receiver |00. A pair of magnets carrying manually adjustable magnetic screens or sleeves, one magnet and sleeve mounted so as to counteract the north-south component of undesired magnetic influences and the other s0 mounted as to counteract the east-west component of undesired magnetic influences, as shown in the Urfer Patent 1,933,194, may be contained in chamber |05. With body portion on a fixed heading, for example north, turret I2 is swung through 360 degrees, and the magnetic screens are manually adjusted and set, as taught by the Urfer patent, so that compenastion for any deviation caused by the turret/body |2 in the indicated bearing on scale l0 may thus be removed.

The mechanical combination. of self-synchronous means 50 and 05, by which a composite indication of azimuth and train is obtained by use of fiducial mark 09, indicator scale 50 and pointer |02, is shown more fully in Figs. 3 and 4.

Indicator housing ||1 contains self-synchronous electrical receivers 00 and 05, which are aligned axially therein. The electrical connections to the receivers are made through a plug receptacle I I0 of conventional form. Housing I I 1 has an enlarged open end ||0 to which is connected, by any suitable means, such as screw studs |20, a conventional instrument facing ring member |2|, having a glass window |22 secured therein by pressure between gaskets |20 and |24, and with index 00 rigidly attached to the upper portion of housing |I1 and extending into the range of window |22. Self-synchronous electrical means 66 and 05 are mechanically secured within housing ||1 by any suitable means. such as studs |25. Rotor member 01 is mounted upon a. hollow shaft |20 which is journalled in suitable bearings ,|21. Shaft |20 is connected to azimuth scale 00 by means of hub member |20 which is welded to, or screwed upon, shaft |25 and attached to azimuth scale 00 by means of screw members |29. Rotation of shaft |20 will, therefore, cause rotation of azimuth scale 60, and bearings in azimuth will bel indicated by the numerical value of scale 00 under index B9. Shaft |00, which is connected to rotor member |00 (see Fig. 2) of self-synchronous electrical means 05, extends through hollow shaft |26 and is connected at its outer end to pointer member |02. Therefore, rotation of rotor |00 will cause rotation of pointer |02. Shaft |00 is supported for rotation within hollow shaft |20 by means of a suitable bearing member I3 I.

The electrical circuit for another embodiment of the invention is shown in Fig. 5. The magnetic compass elements including bowl 04, magnetic pick-up device 31, induction motor 42, etc., are arranged and operate in exactly the same manner as has been described above for the system shown in Fig. 2; and like reference characters have been used to Adenote those elements of this embodiment of the system which are common to the system shown in Fig. 2.

Whenever shaft 30 is rotated due to the change of heading of the carrying vehicle, scale 00' will be rotated to indicate the new bearing under index 59', as stators 03 and 05 are connected in parallel through leads 54 and |40. As above pointed out, 61 controls Scale 50 and thus, the remote indication of bearing may be had. Stator |4| of a receiver |42 is also connected in parallel to stator 63 through leads 04 and |40, thus, rotation of shaft 30 will cause a like angular rotation of rotor |44, which is connected to a shaft |45 driving a pointer |40. An azimuth scale |41, fixed. with respect to the carrying vehicle and having an index or lubber mark |40, is provided so that an indication oi' bearing may be had in cooperation with pointer |40. When blades 19 of switch 02 are thrown to the left. stator 9| is placed in circuit with stator I|2 of electrical transmitter 20 through leads |40 and |50. Rotor |00 of electrical transmitter 20 is rotated by gear I0 which is in mesh with a train |54 which is driven upon rotation of turret I2, (not shown) carrying ring gear |55. As synchronous electrical transmitting motor means 20 is responsive to angular movement of turret I2, then upon rotation of turret I2, rotor 09 drives pointer I0| so that the angle of train of the turret may be read from scale 00' at the pilot's station.

When switch blades 10 are closed to the right, then synchronous electrical transmitting means 20 is out of the electrical circuit and movements of turret |2 are not transmitted to pointer I0|; however, asynchronous electrical transmitting means |5I having a stator |52, a rotor' |50, and a pointer |58 is substituted for self-synchronous transmitting means 20. The housing oi transmitter |5| carries a spur gear |50 upon which is mounted a hollow shaft |51 carrying a pointer |50. Shaft |45, which carries pointer |40, passes through hollow shaft |51 in a manner similar to the shafting arrangement shown in detail in Fig. 3, except that rotors |53 and |44 are both fixed to shaft |45. A hand knob |59 carried by a shaft |50 to which is attached a gear ISI is provided for rotation of gear |50 through a suitable pinion |52. The gunner or commander of the tank may `manipulate knob |50 to cause pointer |56 to assume any desired point on scale |41. Rotor |50 is energized by alternator 40 throuh tion of stator |62 (caused by rotation of gear |66) relative to rotor |63, will cause rotation of rotor 96 and, therefore, pointer |6| andthe point indicated by the position of |66 on scale |41 will be repeated by pointer |6| on scale 63. The pilot of the tank, who may be notified by an auxiliary signal system, such as one involving colored lights, that the gunner has closed switch 32 to the right, mayl steer the new course as indicated to him by pointer changing the heading of the tank until index 66 is rotated by changing the course of the vehicle to agree with pointer IIII.

So far as the pilot is concerned, the indicating system in Fig. is exactly the same as the indicating system in Fig. 2, since pointer |I|| (and such additional pointers such as |62 and |03 as may be provided) will indicate turret train when blades 19 of switch 32 are closed to the left and a newly set course when switch blades 13 are closed to the right. However, the gunner or commander obtains his bearing and train indications by means of one scale, |41, vand pointers |46 and |66. 'Also, he sets any selected course by revolving pointer |66 with respect toscale |41, and indications thereof, with switch blades closed to the right, are transmitted to the pilot by means of pointer lll.

While the present invention has been described as applicable to dirigible tanks, it is apparent that it may be employed in any vehicle, such as an aircraft or battleship, wherein it is of advantage to know the magnetic bearing of the vehicle, and also the magnetic bearing or angle of train of a rotatable turret carried by the vehicle. Further, any number of remote stations may be provided so that bearings may be repeated to any station desired. The present invention has been fully shown and described as employing magnetic needle 36 as the directive element, but the invention is equally well adapted to use as a magnetic compass of the earth inductor type, and in the event that it is so used, iiux gate 31 will be made to respond to the directive inuence of the earths held, and

no magnetic needle will be employed. If the invention is used in the form of an earth inductor compass, obviously bowl 34 and needle 36 will be omitted, but compensation for deviation oi' the earths field due to swing of turret l2 may still be effected through the use of compensating chamber |66.

While an alternating current transmitting and repeating system has been shown for repeating compass and turret bearings in indica-y tors 21, 29 .and 33 it is to be understood that any conventional direct current repeating system may be substituted therefor.

The amplifier 63 may bea vacuum tube ampliiler of any conventional design and is therefore not shown in det-ail. One skilled in the art will understand this without further explanation.

Although only two embodiments of the present invention have been described, it will be understood that many changes may be made without exceeding the scope of the present invention, which should be measured, not bythe particular examples set forth, but by the appended claims.

What is claimed is l. A bearing and train indicator for a vehicle in which said bearing indicator includes a magnetic compass needle, said vehicle including a body portion and a trainablevturret capable of distorting the magnetic'field in the region o! said compass needle deviation compensating means associated with said needle, means controlled by said compass needle indicating the bearing of said vehicle with respect to said magnetic needle, and said train indicator including a. transmitter, a receiver in circuit therewith, an indicator carried by said receiver, and turret rotation responsive means for controlling said transmitter and receiver and for rotating said deviation compensating means to compensate for the distortion of the field in the region of said compass needle for various train angles of said turret.

2. In combination with a vehicle having a body portion and a trainable turret portion carried by said body portion rotatable about an axis of said body portion, a magnetic compass having a compass needle carried by said body portion, said turret portion upon rotation distorting the magnetic field in the region of said compass needle, magnetic deviation compensating means carried by said body portion adjacent said compass and mounted for rotation with said turret portion to prevent deviation of said compass needle, means controlled by said compass for indicating the magnetic bearing of said body portion, index means amxed to said body portion adapted to rotate around said compass controlledV means for indicating magnetic bearing upon changing the -bearing ofsaid body portion, means coacting with said magnetic bearing indicating means for indicating the angle of train of said turretportion, and means controlled by rotation of said turret portion in circuit with and adaptedto rotate said deviation compensating means synchronously with the rotation of said turret portion to thereby simultaneously indicate direction of turret train and compensate for said distortion of the magnetic held in the region of said compass needle during rotation of said turret portion on the body portion.

3. In combination with a vehicle having a body portion, and a turret portion rotatable about an axis of said body portion, a magnetic compass carried by said body portion; said compass in ciuding a magnetic needle, a magnetic pick up device within the influence of the magnetic field of said needle, an induction motor, an electrical transmitting device having a rotor and'a stator carried by said body portion, shaft means adapted to rotate said magnetic pick up device, the rotor of said electrical transmitting device and said induction motor in unison, electrical connections between said magnetic pick up device and said induction motor, said shaft means being rotated by said motor in accordance with changes oi bearing of said magnetic pick up device with respect to said magnetic needle, rotatable means carried by said body portion adjacent said compass for compensating for magnetic deviation of said magnetic needle, a second electrical transmitting device having a rotor and a stator carried by said turret portion, an electrical receiving device having a rotor and a stator carried by the said body portion, electrical connections between the respective rotors and statorsof said second electrical transmitting device and` said electrical receiving device, an indicator carried by the rotor of said receiving device adapted to indicate the Iangle ofturret train, a second electrical receiving device having a stator and a rotor in circuit ret portion is rotated, whereby upon rotation of said turret portion with respect to said body portion, the indicator carried by the nrst of said electrical receiving devices will indicate the angle or train of said turret portion, while compensating for deviation o1' the compass due to turret rotation and the indicator carried by the second oi said electrical receiving devices will simultaneously indicate the bearing of said body portion in azimuth in a common focal plane.

4. In combination with a vehicle having a body portion and a turret portion carried by said body portion rotatable about an axis oi' said body portion, a magnetic compass carried by said body portion, said turret portion upon rotation being capable of distorting the magnetic field in the region of said compass needle, magnetic deviation compensating means, means for moving said compensating means including an electrical receiver having a rotor and a stator carried by said body portion adjacent said compass, said compensating means being moved to prevent deviation of the compass when said turret portion is rotated, ilux valve means responsive to changes in azimuth of said vehicle, a polyphase motor having one phase thereof in circuit with said i'lux valve means and the other phase connected to'a source of power supply, transmitting means including a rotor and a stator, a drive connection between the rotor of said motor and the rotor of said transmitting means, receiving means electrically connected to said transmitting means including a rotor and a stator, a compass card connected to and rotatable by said receiving means rotor, an index member amxed to said body portion adjacent said,compass card, turret angle receiving means mounted in alignment with said compass card including a rotor and a stator, a pointer connected to and rotatable by said turret angle receiving rotor, transmitting means controlled by rotation of. said turret including a rotor and stator, said transmitting means controlling said turret angle receiving means and said means for moving said compensating means stator. so as to energize and rotate the rotors of said deviation compensating means receiver and said turret train receiving means synchronously to compensate for the distortion of the field in the region of said compass needle while rotating said turret portion to indicate angle of train with respect to the said compass card by rotation of said pointer.

5. LA bearing indicator for a vehicle in which the bearing indicator includes a magnetic compass needle, means controlled by said compass needle indicating the bearing of said vehicle with respect to said magnetic needle, said vehicle including a body portion and a trainable support rotatably mounted on said body portion capable of distorting the magnetic field in the region of said compass needle, means connected to said support and responsive to rotation thereof relative to said body portion, means operated by and proportionally to said rotation of said support connected means, and deviation compensating means associated with said compass needle and connected to be controlled by said means responsive to said support connected means for rotating said compensating means to compensate for the distortion of the tleld in the region of said compass needle for various train angles oi said support.

PAUL A. NOXON. 

